The present invention relates to a waveform observing apparatus for sequentially scanning recording means such as an electron beam or a recording pen of a cathode-ray tube, X-Y recorder or the similar planar display apparatus for a plurality of times in a predetermined manner and modulating the recording means in accordance with an input signal to be observed for reproducing the waveform thereof.
Examples of such waveform observing apparatus are oscilloscopes and oscillographs which are being used in various fields. In these conventional apparatus, the electron beam of a cathode-ray tube (hereinafter referred to as a CRT) or the recording pen moving on a recording paper is deflected or moved in orthogonal two directions (X- and Y-axes); one (for example X-axis) represents the time axis to which a sweep signal varying linearly with time is applied; and the other (Y-axis) is controlled by an input signal voltage to be observed. The electron beam or the pen position is deflected or moved in accordance with the input voltage as a function of time and displaying or recording the trace of the input signal waveform on the screen of the CRT or on the recording paper.
The conventional waveform observing apparatus, however, has disadvantages that the use of analog signal processing means limits the measurement accuracy to approximately a few percent which is much lower than 0.1 percent or so required in many high precision applications and that the measurements are not in such a form that is convenient for storage or further arithmetic processing.